This invention relates to image reproduction apparatus and more particularly to such apparatus that is substantially flat in form and which includes solid state devices for reproducing the image.
Cathode-ray tubes (CRT) are well known in the art of video image reproduction and are recognized as an industry standard in the application of a picture reproduction element of a television receiver. It is noted that the popularity of the CRT persists notwithstanding the fact that current developments in the television industry have evolved receivers which employ solid state devices throughout except for reproducing an image. The conventional solid state television receiver therefore becomes a hybrid device in which all drive circuits that operate the picture tube are solid state devices whereas the image reproducing element of the receiver is a hard vacuum tube.
Many advantages would naturally accrue through the use of a solid state picture tube. Perhaps the most notable advantage would be the increased compatibility of the solid state drive circuitry with a solid state picture tube. In this connection, it is noted that television receivers are relatively bulky devices for their picture size which arises as a result of deflection requirements for scanning a conventional CRT. As a result of wider deflection angles, the length of the CRT has been reduced and in this way the cabinet depth of a television receiver has been made correspondingly smaller. There is, however, an apparent need to still further reduce cabinet sizes in order to provide relatively large reproduced images without incurring the disadvantage of requiring considerable cabinet depth to support the CRT. It would therefore be extremely useful to have a compatible solid state picture tube that is substantially flat in form in order to reduce the space requirements of the conventional television receiver. A flat picture tube would therefore permit fabrication of a television receiver as a wall mounting apparatus requiring little more space than a framed picture.
Increased compatibility carries with it additional features that would result in improved operation of the picture tube with reduced hazards. For example, a solid state picture tube of the type proposed herein would not require a large evacuated glass envelope that carries with it certain hazards. One of the more serious hazards, of course, is the danger of implosion as a result of the vacuum pressure within the envelope.
Other advantages result in more simple receiver circuitry and improved operation as a consequence. Thus, high second anode voltages would no longer be required, together with corresponding scanning circuitry, dynamic convergence coils, focus circuits and the like. The effect of poor stability in any of these circuits would result in a degraded picture which can be avoided with the flat picture tube.
As a result of avoiding high voltage second anode voltages, X-radiation is reduced together with its attendant hazards thus providing still another advantage.